/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8                               :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
│                                                                              │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/syscall-nt.internal.h"
#include "libc/intrin/dll.h"
#include "libc/intrin/maps.h"
#include "libc/nt/memory.h"
#include "libc/runtime/runtime.h"
#include "libc/stdio/sysparam.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/errfuns.h"

#define SYNCRANGE_CONTAINER(e) DLL_CONTAINER(struct SyncRange, elem, e)

struct SyncRange {
  char *data;
  size_t size;
  struct Dll elem;
};

textwindows static void *sys_msync_nt_malloc(size_t size) {
  return HeapAlloc(GetProcessHeap(), 0, size);
}

textwindows static void sys_msync_nt_free(void *ptr) {
  HeapFree(GetProcessHeap(), 0, ptr);
}

textwindows int sys_msync_nt(char *addr, size_t size, int flags) {

  // validate arguments
  if ((uintptr_t)addr & (__pagesize - 1))
    return einval();

  // round up size
  size += __pagesize - 1;
  size &= -__pagesize;

  // create list planning which ranges we need to sync
  __maps_lock();
  struct Map *map;
  struct Dll *ranges = 0;
  if (!(map = __maps_floor(addr)))
    map = __maps_first();
  for (; map && map->addr <= addr + size; map = __maps_next(map)) {
    if (map->flags & MAP_ANONYMOUS)
      continue;  // msync() is about coherency between file and memory
    char *beg = MAX(addr, map->addr);
    char *end = MIN(addr + size, map->addr + map->size);
    if (beg >= end)
      continue;  // didn't overlap mapping
    struct SyncRange *range;
    if ((range = sys_msync_nt_malloc(sizeof(*range)))) {
      range->data = beg;
      range->size = end - beg;
      dll_init(&range->elem);
      dll_make_first(&ranges, &range->elem);
    }
  }
  __maps_unlock();

  // perform the i/o operation
  int rc = 0;
  struct Dll *e, *e2;
  for (e = dll_first(ranges); e; e = e2) {
    e2 = dll_next(ranges, e);
    struct SyncRange *range = SYNCRANGE_CONTAINER(e);
    if (!FlushViewOfFile(range->data, range->size))
      rc = -1;
    // TODO(jart): FlushFileBuffers too on fd handle if MS_SYNC?
    sys_msync_nt_free(range);
  }

  return rc;
}
